Heart disease is a significant health condition affecting millions of people worldwide. Cardiomyopathy (cardio meaning “heart” and myopathy meaning “muscle disease”) refers generally to a group of disorders that directly affect the muscle of the heart walls, or myocardium. As a result, all the chambers of the heart are negatively affected and the ability of the heart to function as a pump is disrupted, thereby resulting in inadequate or inconsistent blood flow to the various organs or tissues of the body.
Generally, one of three types on non-ischemic heart disease, that is, heart tissue damage not caused by heart attack, may be present in a patient: dilated congestive, hypertrophic, or restrictive. Dilated congestive cardiomyopathy damages the fibers of the heart muscle and weakens the walls of the heart's chambers, resulting in the chambers losing some capacity to forcibly contract and pump blood through the circulatory system. Thereafter the chambers of the heart enlarge or dilate to compensate for the decrease pumping efficiency. The enlargement of the chamber may result in heart failure. Hypertrophic cardiomyopathy is characterized by a disorderly growth of heart muscle fibers resulting in the walls of the heart chambers becoming thick and bulky. Wall thickening is most pronounced in the walls of the left ventricle, the heart chamber which pumps blood to through the aorta to vital organs and tissues of the body. The thickening walls result in the trapping of blood within the heart during contraction, thereby providing an inadequate blood supply to the brain or other vital organs. Restrictive cardiomyopathy causes abnormal cells, proteins, or scar tissue to infiltrate the muscles and structures of the heart, causing the chambers to become stiff and bulky, thereby restricting blood flow to the heart.
Massive or multiple heart attacks may also lead to severe heart damage as a result of a disruption of the blood supply to the heart muscle. The heart damage resulting from heart attacks may include functional impairment and structural abnormalities similar to those found in other types of cardiomyopathy. This type of heart disease, resulting from coronary artery disease, is called ischemic cardiomyopathy (ischemic meaning “lacking oxygen”).
Patients with ischemic cardiomyopathy may initially be treated with medication to relieve heart failure symptoms and to improve blood flow through the diseased arteries. These medications may include nitroglycerin, calcium channels blockers, and angiotensin—converting enzymes (ACE) inhibitors. When symptoms of heart failure and coronary artery disease cannot be controlled with medications coronary angioplasty or surgery may be considered. Some patients, due to the advanced state of heart disease, may become too ill to survive conventional coronary surgery. Non-surgical procedures such as percutaneous transluminal coronary angioplasty, laser angioplasty, and atherectomy have been developed. One alternative to the aforementioned procedures is known as Transmyocardial Revascularization (TMR). In such procedures, channels are formed in the ventricle wall of the heart. These channels provide blood flow to ischemic heart muscle.
Pioneering methods for performing TMR involved the use of needles for physically puncturing holes in the heart wall. These methods resulted in only a temporary delivery of blood to the myocardium because the holes quickly healed at the endocardium, preventing oxygenated blood from entering the myocardium. One of the more recent and exciting methods of performing TMR is through the use of lasers. It has been observed that new holes or channels formed in the heart wall by a laser tend to heal at the epicardium, which prevents blood loss, and promote blood perfusion into the ischemic region of the myocardium.
Lasers have proven to be a widely useful and applicable tool in modern medical techniques, particularly in minimally invasive surgical procedures. A laser is able to produce high-intensity and high-energy light at a single frequency. The energy of laser light is measured in joules (J), or waft-seconds (W-s), and the power of a laser is measured in wafts (W).
One of the conventional surgical apparatus for performing TMR consists of a laser and an optical fiber. A surgeon places the end of the optical fiber against the epicardium to ensure that all the laser light is focused at the desired point, and then the laser is fired. In order to form the new channel completely through the heart wall and into the chamber, the surgeon needs to tactilely urge the optical fiber into and through the epicardium, the myocardium, and the endocardium. Because of the nature of ischemic cardiomyopathy, the thickness of the diseased myocardium is irregular and greater than normal. Accordingly, the surgeon needs to tactilely urge the optical fiber through the heart wall at each location.
Execution of TMR procedure takes a certain amount of time to accomplish safely and involves a certain amount of guesswork on the part of the surgeon. This procedure is complicated by the beating of the heart. Accordingly, the firing of the laser needs to be synchronized with the beating of the heart and the device should be maintain its position with respect to the epicardium. In addition, irregularly shaped holes may result if the surgeon does not urge the optical fiber into the tissue at a constant rate or if the handpiece disengages the epicardium. For example, a cavity within the new hole may be formed if the surgeon slowed down or paused briefly at a particular location because more tissue at that location would be ablated by the increase in laser energy emitted over time. In addition, the increase in emitted laser energy may cause excessive trauma to the surrounding tissue at that location.
With a channel formed, the surgeon may treat the area with a medicament. For example, an angiogenic material may be deposited or injected into the channel or surrounding tissue. As such, the ability to isolate the channel or surrounding area is preferred, thereby preventing medicament “washout”. Currently, methods of preventing medicament washout have generally proven to be unsuccessful.
Thus, there is a need for a system of delivery system capable of stabilizing tissue, forming a channel within the tissue, and delivering medicament to the channel or the surrounding area. It is further desirable to have a system capable of isolating an area of interest prior to delivering medicament thereto, thereby preventing medicament washout.